The broad objective of the proposed research is to identify the central nervous mechanisms by which severe acute stress produces persistent changes in the behavior and physiology of animals. The proposed experiments are designed to study the metabolism of behaviorally active brain monoamines during the period of recovery after various types of acute stress. In previous research on this project it has been established that there is a persistent increase in the utilization of hypothalamic norepinephrine (NE) lasting for prolonged intervals after the termination of an acute period of the stress of forced running in rats. There is reason to suspect that this metabolic change is related to a persistent emotional response to the aversive stimulation of stress. One aim of the proposed research therefore is to study the synthesis and metabolism of brain NE after various types of aversive stimulation that produce strong emotional reponses. A second aim is to determine whether persistent changes in NE metabolism seen after acute stress are unique to the hypothalamus or occur in other areas of the brain involved in emotional and automatic responses, such as the limbic system. A third objective is to determine if drugs that are effective in reducing emotional responses such as the benzodiazepine tranquilizers, chlordiazepoxide and diazepam, can inhibit the above post stress neurochemical changes.